Well, they are called a "Glider Kit" and are gaining favor with small and large truck fleets.
The kits are sold by Daimler in three configuations,
1) New dressed cab, frame, front axle, radiator, fuel tanks etc.
These are designed to accept an engine, transmission and rear axles from a similar donor vehicle.
2) A "Roller" kit. This includes everything above plus Reman rear axles and suspension in place. Designed to accept a donor motor and transmission.
3) A "Powered Glider". This includes everything from number 1) plus has a Reman engine installed at the factory. Currently Cat, Cummins and Detroit Diesel engines are offered. The transmission and rear axles are from a donor vehicle. This is what we have been selling, 15 of them so far this year.